ARAB-US RELATIONS - Sept. 11 - Terrorists Hit US.

In unprecedented terrorist attack, three hijacked aircraft hit the Towers of the World Trade Centre in New York and the Pentagon in Washington, and the fourth hijacked plane crashes in Pennsylvania, killing more than 5,000 people. Below is the chronology of the tragic events:

08.45 NY time (12.45 GMT) - The American Airlines Boeing 767, flight 11, hijacked after takeoff from Boston en route to Los Angeles with 81 passengers and 11 crew members on board, hits the North Tower of World Trade Centre in New York's financial district causing massive explosion.

09.03 The United Airlines Boeing 767, flight 175, also hijacked from Boston en route to Los Angeles with 56 passengers and nine crew on board, hits the South Tower of World Trade Centre.

09.30 Pres. Bush declares: "Today, we've had a national tragedy. Two airplanes have crashed into the World Trade Centre in an apparent terrorist attack on our country. Terrorism against our nation will not stand". He vows an all-out hunt for the perpetrators.

09.40 The third plane, the American Airlines Boeing 757, flight 77, hijacked from Dulles Airport in Virginia and also bound for Los Angeles with 58 passengers and six crew on board, hits Pentagon in Washington, with part of the building collapsing later. White House and Pentagon evacuated.

09.43 Abu Dhabi television reports receiving a phone call from the Democratic Front for the Liberation of Palestine claiming responsibility for the attacks on the World Trade Centre. Reports are later denied by DFLP.

09.50 All Airports across the US shut down. New York Stock Exchange is shut indefinitely.

10.00 South Tower of New York World Trade Centre collapses.

10.05 United Airlines 93, Boeing 757 from Newark, New Jersey, bound for San Francisco, with 38 passengers and seven crew on board crashes south-east of Pittsburgh in Western Pennsylvania.

10.12 British PM Blair holds emergency talks by Cabinet's emergency committee - Cobra. He calls the attacks "the most terrible shocking event".

10.35 New York - Second tower collapses. In the UK, Canary Wharf evacuated.

11.04 UN HQ in New York evacuated.

11.57 The Taliban holds press conference, denying Osama Bin Ladin responsibility.

12.48 Hamas denies any connection to attacks.

17.30 Salomon Smith Barney's 47 story building collapses.

About 50,000 people worked in the World Trade Centre and 150,000 more passed through the complex every day. The twin 110-floor towers housed the offices of more than 400 companies from 25 countries. The attacks cause the severe damage or destruction of 20% of Manhattan's office space.